Magnetic chuck



Jan. 16, 1923.

D S. WALKER. MAGNETIC CHUCK FILED MAR. 28. I919.

Patented Jan. 16, 1923.

UNITED STATES PATENT OFFICE.

OAKLEY S. WALKER, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO 0. S. WALKER 00., OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

MAGNETIC CHUCK.

Application filed March 28, 1919.

To all whom it may concern.

Be it known that I, OAKLEY S. WALKER, a citizen of the United States, residing at Worcester, in the county of Worcester and Commonwealth of Massachusetts, have in vented a new and useful Improvement in a Magnetic Chuck, of which the following, taken in connection with the accompanying drawings, is a specification.

The present invention relates to the construction of a magnetic chuck for the sup port and retention of iron and steel pieces of work which are to be subjected to Various operations, such as grinding and the like. The invention contemplates a work holding face for said chuck constituted by a large number of pole pieces in the form of parallel oppositely magnetized strips, which are so arranged in relation to the energizing devices of the chuck as to give a finely divided work holding face especially adapted for the retention of small pieces of work. The features of the invention are fully set forth in the following description, reference being had to the accompanying drawings, in which Fig. 1 is a partial plan view of a chuck embodying the invention.

Fig. 2 is a vertical sectional view of the chuck.

Figs. 3 and 4 are perspective views of two different kinds of pole pieces used in the assemblage of the chuck, and

Fig. 5 is a perspective view showing the bottom or under side of the face plate of the chuck.

Like reference characters refer to like parts in the different figures.

Referring to the drawings and particu larly to Fig. 2, the chuck is shown as constituted by a rectangular casing or shell 1, providing an interior space for the magnetizing instrumentalities of the chuck. As herein shown, these magnetizing instrumentalities take the form of a single core casting 2, which provides a plurality of spaced transverse projections or cores 3, 3, whose upper surfaces are substantially flush with the upper edge of the shell 1. To this end the core casting 2 is suitably supported upon a plurality of screws 4, 4 made of brass or other nonmagnetic material, which screws are let in through the bottom of shell 1, and are adjustable to vary the position of the core casting. In this Way the core casting 2 is main- Serial No. 285,864.

tained entirely out of magnetic contact with the shell 1 and hence the latter is unm-agnetized.

Suitable windings or coils of wire 5, 5 are disposed upon the several cores 3, 3, in such a manner as to impart opposite magnetic polarity to adjacent cores; that is, as shown in Fig. 2, every alternate core will be magnetized to a positive polarity while the remainder of said cores will be magnetized to a negative polarity. As a result, the top surfaces of the cores 3, 3, with which the pole pieces of the face plate are brought into contact, as hereinafter described, are adapted to energize said pole pieces according as the latter may contact with positive or negative cores.

The face plate of the chuck is constituted by a rectangular frame 6 which corresponds with and is adapted to be superposed upon the upper edge of the shell 1. The rectangular space inclosed by the frame 6 is filled with two sets of pole pieces, those of one set adapted to make contact with the positive cores 3, and those of the other set adapted to make contact with the negative cores 3. These pole pieces are disposed edgewise in the frame 6, their ends being entirely insulated from said frame by the usual gaps of non-magnetic material 7, 7. One of the pole pieces of the positive set is shown by way of example in. Fig. 3, the same consisting of a relatively narrow strip 8 having a plane upper edge corresponding to the work holding face of the chuck. The lower edge of strip 8 is cut away at intervals as shown at 9, corresponding to the location of the negative cores 3, 3 when the strip 8 is in place. That is, the lower edge of the positive strip 8 is so formed as to make contact only with the positive cores 3, 3, and contact with the negative cores 3, 3 is avoided by cutting the edge away as shown at 9, 9. In order to increase the contact surface of each of the strips 8, 8 with the positive cores 3, 3, feet 10, 10 are formed laterally on the contact portions, these feet being at right angles to the plane of the strip so as to increase the area of contact between the strip and the positive cores.

Alternating with the positive strips 8, 8 are the negative strips 12, 12, which are of the same construction as the positive strips 8, 8 except that their lower edge cutaway portions are so situated as to bridge the positive cores 3,3 and the feet 10, 10. it follows, therefore, that the strips 12, 12 make contact only with the negative cores 3, 3, said strips being formed with feet 13 similar to the feet 10, in order to increase the contact area. The alternating strips 8 and 12 are separated from each other by the usual gaps of non-magnetic material 1 1, as shown in Figs. 1 and 5, said. material being preferably poured in a molten state between the strips and allowed to solidify, in the usual manner, so as to unite all of said strips with the frame 6, thus completing the face plate. ll hen said face plate is secured in place on the shell 1 as by holding bars 15, the feet 10 of the strips 8 make contact with the positive cores 3, 3, while the feet 13 of the strips 12 make contact with the negative cores, 3, 3, and hencethe two sets of strips 8 and 12 are oppositely polarized giving a very finely divided work holding face of maximum holding power.

The preferable manner of arranging the strips 8 and 12 is shown in Fig. 5, where, it

i will be noted, the feet 10 and 13 are of a width corresponding to the combined thickness of the two strips 8 or 12 and two layers of non-magnetic material 14, Vllith the arrangement shown, it is possible to use the two strip patterns interchangeably, simply by reversing one or more of the strips of each set, as regards the direction of their feet, and interposing between the reversed strips and their mates in the same set a single strip without lateral projecting feet, such as shown at 16 or 17, Fig. 5. A strip of this character, as indicated at 16 or 17, is made in precisely the same manner as the other strips 8 and 12, except for the fact that it is not provided with any lateral feet and in the direction.

I claim,

1. In a magne ic chuck, a series of parallel strips coinpi 'ng a work holding face, said strips hai 'ing lateral extensions for contact with magnetizii'ig cores,

2. In a magnetic chuck, a series of parallel strips coi'i'i 'irising a work holding face, said strips having lateral extensions for contact with magnetizing cores and being cut away between said extensions to avoid contact with other magnetizing cores.

3. Ina magnetic chuck, a shell, a face plate supported thereon, magnetizing means for said face platev within said shell, and means for adjustably supporting said magnetizing means for movement into contact with said. face plate.

4:. In a magnetic chuck, shell supporting a face plate, magnetizing means for said face plate within said shell, and means operable from the exterior of said shell for pres ing said magnetizing means into contact with said face plate.

Dated this twentieth day of March, 1919.

OAKLEY S; lVALKER. lVitnesses N ELLIE lVnALnN, Pnzracorn CoirnnRBAoi-r, 

